Method and apparatus for cleaning sewage



March 7, 1939. 5 TQLMAN METHOD AND APPARATUS FOR CLEANING SEWAGE Filed April 2, 1956 5AMUEL. L TOLMAN,

I BY

ATT'X I. l I

Q C i a mm lm m PM Id Patented Mar. 7, 1939 UNITED STATES Samuel L. -Tolman, Columbus, Ohio, assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Application April 2, 1936, Serial No. 72,358

14 Claims.

This invention relates to an improved method and apparatus for cleaning sewage and more particularly to a method and apparatus for removing grit from.sewage.-

:. An object of the invention is to provide an improved method and apparatus for removing grit from sewage whereby there will be no formation of stagnant areas in the grit settling tank, thus avoiding accumulation of putrescible 1-1) organic matter.

Another object of the invention is to provide a method and apparatus for cleaning and removing grit from sewage whereby liquid can flow over an inclined surface adjacent the point of grit influent sewage.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawing,

Fig. l is a. sectional elevational view of an apparatus comprising my invention;

Fig. 2 is a plan view of the device of Fig. 1;

Fig. 3 is a sectional view taken on the line 33 of Fig. 1 looking in thedirection of the arrows;

Fig. 4 is a sectional view taken on the line 44 of Fig. 1 looking in the direction of the arrows; and

Fig. 5 is a sectional plan view taken on the line 5-5 of Fig. 1 looking in the direction of the arrows.

In the treatment of sewage, particularly where the putrescible organic matter is digestedin a digester', it is necessary first to remove the inorganic grit from the .sewage before it is fed to the digester. The method and apparatus herein disclosed relates to the removal of this grit from the sewage.

It has been found in practice that there is a tendency in most grit removers toward the formation of quiescent or stagnant areas with a consequent accumulation of putrescible organic matremoval, and flow directly into the stream of- Adjacent one end is an efiluent conduit l3 through which the efiluent sewage will fiow from the tank Ill. Adjacent the other end is an in-- fluent conduit l4 adapted to direct the incoming sewage into said tank It). As is clearly illus- 5' trated in the drawing, the tank l is'preferably of an elongated construction and has a pair of bottom tapering side walls I5, l which form continuations of the side walls H, H and lead to the bottom l2 of the tank II] which is of reduced width.

As best seen in Figs. 1, 3 and 5 of the drawing the influent conduit I4 is divided into two parallel branches l6, [6 by a centrally disposed c01- umn I! which has a pointed deflecting portion I8 adapted to guide the influent from the conduit [4 into the branches Hi. The column I! has a flat upper surface which is inclined both to the horizontal and to the'vertical, which surface extends entirely between the side walls II of the tank I0 adjacent the top portion of said tank, as best illustrated at [9' in Fig. 3. The central portion of the column ll, of course, does not extend completely between the side walls I I because it is terminated by the influent branches I6, 16. As a consequence, the column I! has side edges 20, 20 which define extremities of the branches l6; I6, and the extended portion IQ of said column has bottom edges 2|, 2| which likewise define extremities of the influent branches l6, I6.

Associated with the tank I 0 is a conveyor which may be generally of the type disclosed and claimed in the application of R. E. Briggs for Material treating apparatus, Serial No. 701,550,. filed December 8, 1933. Briefly described said apparatus comprises a conveyor formed of a pair of continuous chains 22, 22 adapted to ride over sprockets 23, 24, 25 and 26. Said sprockets 23, 24 and 25 are mounted upon suitable shafts within the tank H], the shafts for sprockets 23 and 24 beingseen at 2'! and 28 respectively in Fig. 4. Said shafts are, of course, mounted on appropriate brackets seen at 29 and 30, which brackets are rigidly supported by the walls of the tank It).

Mounted upon the continuous chains 22, 22 is a plurality of flights, as best seen in Fig. 2 of thedrawing, said chains carrying a pair of flights 31 formed in the shape of a plow which, 7 when moving along the bottom l2 of the tank I 0, would tend to move the settled grit outwardly. This pair of flights 3| will be followed by a pair of flights 32 which are disposed to move the material inwardly along the bottom "wall of the tank It. A number of such pairs of flights 3| and 32 will be provided to cause a to and fro movement of the grit on the bottom l2 of tank I0, thereby to wash it and remove therefrom any putrescible organic matter which tends to adhere thereto. This washing action will be effective throughout substantially the entire length of the tank l0, and will free the inorganic grit of adhering or anic matter. 1

The chains 22, 22 also carry flat transversely extending flights 33, which will scrape the grit along the bottom of the tank It in the direction of the arrow 34, or from the efliuent end to the influent end of such tank In. The chains 22 travel outside of the tank It under the influence of sprockets '26 and thus the flights travel along the inclined surface forming the top of the column IT, as directed by sprockets 25 and 26. Asv

a consequence, in the operation of the conveyor, the washed grit will be conveyed up the inclined surface forming the top of column I! and will be conveyed to a trough 35 from which it will be directed to a transversely extending belt conveyor 33 by a chute 31. An electric motor 38 will be provided for operating the conveyor including the 30 g In the operation of the device comprising my invention, the sewage will be introduced into the tank ill from the influent conduit M by way of the influent branches l6, l6. Said sewage will then flow through the tank ID at a rate which 3 will favorsettling of the grit, but will not favor settling of the organic material. As a consequence, the grit will settle on the bottom l2 being directed thereto by the inclined side walls [5. The eflluent sewage thus freed of grit will flow 40 from the tank l0 by way of the efliuent conduit l3. The conveying mechanism through the operation of the flights 3| and 32 will scrape the settled grit to and fro on the bottom [2 to free it of adhering organic material. The flights 33 45 will move the grit longitudinally of the tank l0 along the bottom l2 and up the inclined surface forming the top of the column ll. As the grit moves up said inclined surface any water which is moved therealong by the flights 33 will flow laterally of said surface and over the edges 20 into the path of the incoming sewage. Such fluid as flows laterall'ypf the flights 33, when any of said flights is riding on the extended portion IQ of said inclined surface will flow laterally ,of said flights .and down said inclined surface over the edges 2|, 2Itinto the branches l6, It. It will thus be noted that thereis no place within the tank It) in which quiescent or stagnant areas can be found which would encourage an accumulation of putrescible organic matter. This insures the prompt removal of organic matter from the tank Ill, and results in 4a directing of the fluid whichzflows from the. inclined surface on top of of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore wish not to be restricted to the precise construction herein disclosed.

75 Having thus described and shown an embodiniake ment of my invention, what I desire to secure by Letters Patent of the United States is:

1. The method of cleaning sewage grit comprising introducing grit containing sewage into a chamber favoring settling of the grit, conveying the settled grit up an inclined surface and out of said chamber at the end of said chamber where the sewage is introduced, and permitting the liquid to separate from the grit and flow laterally on said inclined surface and directly from said surface into the path of the influent sewage, while removing the efiiuent from said chamber at a remote point from said inclined surface.

2. The method of cleaning sewage grit comprising introducing grit containing sewage into a.

chamber favoring settling of the grit, washing the grit on the chamber bottom to free it of organic matter, conveying the freed grit up aninclined surface and out of said chamber, and permitting the liquid to separate from the grit and flow laterally on said inclined surface and directly into raw sewage flowing into said chamber, while removing the efliuent from said chamber at a remote point from said inclined surface.

3. The method of cleaning sewage grit comprising introducing grit containing sewage into a chamber favoring settling of grit by directing the influent into a pair of parallel paths of entrance into the chamber, conveying the settled grit up an inclined surface between said parallel paths while permitting a flow of fluid laterally on said inclined surface and directly into both paths of the influent while the grit is removed from said chamber.

4. In apparatus for removing grit from sewage, the combination with an elongated settling tank, a sewage influent conduit at one end and an efliuent conduit at the other end, continuous scraper conveyor means in said tank for removing settled grit and conveying it out of said tank adjacent said influent conduit, said tank being constructed and arranged to direct the influent into said tank along two separated parallel paths between which said conveyor removes the grit.

5. In apparatus for cleaning and separating grit from sewage, the combination with a settling tank,

of an influent conduit, an eflluent conduit, a continuous' flat inclined surface adjacent said influent conduit extending from below the liquid level of said tank to a position above said liquid level and having an edge common with an edge of said influent conduit, and continuous conveyor means constructed and arranged to clean settled grit of attached organic material and convey said grit out of said tank up said inclined surface, while superelevated liquid flows from said grit back into the liquid in said tank.

'6. In apparatus for separatinggrit from sewage, the combination with a settling tank, of an influent conduit, an eiiiuent conduit, a continuous flat inclined surface adjacent said influent conduit extending from below the liquid level of said tank to a position above said liquid level and having side and bottom edges common with a side and top edge, respectively, of saidinfluent con-,

duit, and conveyor means constructed'and" arranged to corivey settled grit out-of said tank up.

said inclined surface. i

'l. A settling tank for sewage comprising a tank, an influent conduit, an efiuent conduit, and means providing an inclined flat surface adjacent and positioned laterally of said influent conduit providing a supporting surface for material to be removed and extending above the normal liquid level of said tank, said supporting surface having at least one edge exposed directly to said influent conduit at one end of said tank and an influent conduit whereby fluid may flow laterally along said supporting surface and into the inf fluent stream of sewage.

8..- A-settling tank for sewage comprising a tank, an influent conduit, and means providing an inclined surface adjacent said influent conduit providing a supporting surface for the removal of settled material, the inclined surface presenting side and bottom edges adjacent said influent conduit whereby fluid may flowfromsaid in- 1 clined surface directly into the path of the influent flowing into said tank through said'influent conduit. v

9.'A grit settling tank for'sewage comprising an elongated tank having a substantially horizontal bottom, an;'influent conduit, an eiiiuent conduit, means adjacent said' influent conduit dividing it into branchesand providing a surface inclined to the horizontal between said branches and forming a continuation of said bottom.

10. A grit settling tank for sewage comprising an elongated tank, an influent conduit, and efliuv ent conduit, and means dividing said influent' conduit into two branches and providing a continuous inclined surface extending as 'a continuation of the tank'bottom and extending to the top of said tank above the normal liquid level of said tank, said means being so constructed and arranged that said branches will lead to said tank with one branch on each side of the bottom pore tion of said inclined surface.

11. In apparatus for removing -t from sewage, the combination with an elongated tank, said tank having a flat bottom and diverging sidev walls, of an influent conduit at one end of said tank, means dividing said conduit into two paths and forming an inclined surface continuing from said bottom and upwardly beyond the normal liquid level of said tank, continuous conveying means in said tank constructed and arranged to convey settled material along said tank bottom and out of said tank by conveying it up said incline, andvmeans for driving said conveying' means.

12. A grit settling tank for sewage comprising an elongated tank having a-flat horizontal bot- Y side wallshaving tom and upwardly extending inclined portions leading to said flat bottom, an

elliuent conduit at the other end, and means dividing said influent conduit into two branches each aligned with an inclined portion of opposite side walls and thus aligned at opposite sides of said flatbottom and providing a continuous inclined'surface extending as a continuation of said tankbottom and extending above the norat one end of said tank and an influent conduit at the other end thereof, means forming an inclined surface which is an extension of said flat bottom and extends upwardly above the normal liquid level 'in said tank and, divides said influent' conduit into two branches one on each side of .said inclined surface with each branch aligned with a converging portion of the opposed side walls and thus aligned at opposite sides of said flat bottom, and continuous scraper conveyor means for conveying material along said flat bottom and up saidincline and out of said tank.

-14. In apparatus for cleaning and separating grl-t from sewage, the combination with a grit settling tank having an upwardly extending wall adjacent one end and side walls having tapered portions leading to a bottom wall of reduced width, and having influent and efliuent conduits providing for a flow of sewage into and out of said tank, of aconveyor having laterally extending flights adapted'to scrape said bottom wall Of reduced width and to convey settled grit therealong and out of said tank by conveying it along said upwardly extending wall, a pair of rails spaced apart a distance to carry the upper run of said conveyor by supporting the ends of 'said flights and positioned above said inclined portions of said side walls, means supporting said rails from said side walls, and means for driving said conveyor. v ShM'UEL L. TOLMAN. 

